1. Field of the Invention
The present invention relates to a vibration detecting apparatus, and more particularly to a vibration detecting apparatus and method thereof used for a drum-typed washing machine.
2. Description of the Related Art
Generally, a washing machine is an apparatus capable of washing laundry by performing the washing, rinsing and drying processes according to predetermined algorism, and is classified into a pulsator-, washing rod or agitator-, and drum-typed washing machine.
In particular, the drum-typed washing machine is used widely, since damaging rate of laundry is lower than other kind of washing machine and washing liquid to be used is of small quantity.
The constitution of the common drum-typed washing machine comprises, as shown in FIG. 1, a body 1, a tub 2 fixed within the body 1 by a damper (not shown), a drum 3 for conducting washing process, in which the drum is inserted into the tub 2 and rotated by operating force of a motor via a belt, a thermistor 4 for detecting a temperature of washing liquid supplied into the drum 3, a detergent container 5 provided for inputting a detergent into the drum, a liquid feed pipe 6, connected with the detergent container 5, for supplying washing liquid, a drainage pipe 7 for extracting the washing liquid used in the washing process, a pump 8, connected with one end of the drainage pipe 7, for pumping the washing liquid, and drainage hose 9.
With construction of the drum-typed washing machine described above, an user opens a door (not shown) attached to the front of the body 1 and puts the laundry into the drum. And then, when the user inputs the washing order, the washing liquid is filled into the drum 3 through the detergent container 5 and liquid feed pipe 6.
And, if a level sensor detects that the washing liquid is filled by a predetermined level corresponding the inputted laundry, the detected value is outputted to a control section. Wherein, a Colpitts oscillating circuit is generally used as the level sensor, by which a oscillatory signal is converted into the level to detect the supplied water volume.
The Colpitts oscillating circuit comprises, as shown in FIG. 2, a bobbin having a moving path in an inner periphery thereof, a core reciprocally movable along the inner periphery by the fluctuation of water pressure, a coil having inductance variable depending upon the reciprocating movement of core wound on the outer periphery of the bobbin, and two condensers C1 and C2.
The method of detecting the level of washing liquid by using of the Colpitts oscillating circuit shown in FIG. 2.
When the core rod is inserted into the bobbin, on which the coil is wound in a constant spacing and a desired times, the inductance value L of coil is changed by the inserted length of the core rod into the bobbin.
The Colpitts oscillating frequency is changed according to the inductance change of coil. At that time, the core rod is pushed into the bobbin by the pressure of the washing liquid.
The prior art washing machine is designed in such a way that the level of washing liquid is determined by detecting the frequency generated between the core rod inserted into the bobbin and the coil wound on the bobbin.
The control section determines whether the feed of washing liquid is completed according to the above oscillatory signal, and operats the motor 10 to progress the washing process.
When the washing process is completed, the washing liquid is drained outwardly by the pump 8 through the drainage pipe 7 and drainage hose 9. And, when the drainage process is completed, the rinsing and drying processes are progressed.
If the laundry is uniformly distributed in the drum at the drying process, noise generates. At that time, if vibrating magnitude is in exess of a desired level, it can be happend a problem of deteriorating of the drying capability or undoing of the drying process.
In order to determine the vibrating magnitude, the common drum-typed washing machine must include a separate vibration sensor.
FIG. 3 shows one example of the vibration sensor, in which a piezo film having a oscillating weight is shown. The operating principle of the vibration detecting circuit using the piezo film will be now descrived.
If the vibrating magnetude of laundry in the drum of washing machine increases, the piezo film 100 is oscillated by the inherent property of film 100″ supporing weight of the weight, thereby a desired voltage being generated by the oscillation of piezo film 100.
The volage generated from the piezo film 100 is amplified by the voltage amplifying circuit 200, and applied to the vibration detecting circuit 300 of a controller, in order to detect the vibration.
FIG. 5 shows the output voltage of the piezo film produced from the vibration detecting circuit 300 shown in FIG. 4. The piezo film is oscillated by the exterial vibration, thereby generating a desired current voltage.
If the washing machine is provided with any separate vibration sensor, the cost of the drum-typed washing machine increases.